1. Chemistry for Biology Biology ~ Edgar

2. Figure 2.1 The hierarchy of biological order from atom to organism

3. Figure 2.2b

4. 10. *Water is a good solvent in living organisms. 1 10 9. Hydrogen bonds are stronger then covalent bonds. 9 2 8. An atom that has gained or lost electron is called an ion. 1 10 7. If solution-A has a pH of 2 and solution-B has a pH of 5 then solution-B is a stronger base then solution-A 2 9 6. *Atoms in a water molecule are held together by the sharing of electrons. 2 9 5. *Ice floats because water molecules in ice are more tightly packed then in liquid water. 10 1 4. *If the atmos in a molecule share electrons equaly, the molecule is said to be non-polar. 1 10 3. A bathtub full of lukewarm water may hold more heat than a teakettle full of boilling water. 3 8 2. The smallest particle of an element is a molecule. 10 1 1. Table salt, water, and carbon are all compounds. 8 3 FALSE TRUE

5. Table 2.1 0

6. LE 2-3 Sodium Chlorine Sodium Chloride

7. Figure 2.5 Two simplified models of a helium (He) atom

9. Figure 2.10 Electron configurations of the first 18 elements

10. Figure 2.12 Covalent bonding in four molecules

11. Figure 2.12x Methane

14. Figure 2.13 Polar covalent bonds in a water molecule

15. Figure 2.14 Electron transfer and ionic bonding

16. Figure 2.15 A sodium chloride crystal

17. Figure 2.16 A hydrogen bond

18. LE 2-4a 2 2 2 Protons Neutrons Electrons Helium atom Mass number = 4 6 6 6 Protons Neutrons Electrons Carbon atom Mass number = 12 Electron cloud Nucleus 2e – 6e –

19. Table 2.4

20. LE 2-6a Electron Outermost electron shell (can hold 8 electrons) First electron shell (can hold 2 electrons) Hydrogen (H) Atomic number = 1 Carbon (C) Atomic number = 6

21. LE 2-6b Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8

22. LE 2-7 Transfer of electron Na Sodium atom Cl Chlorine atom Na  Sodium ion Cl  Chloride ion Sodium chloride (NaCl)

23. LE 2-7a-1 Transfer of electron Na Sodium atom Cl Chlorine atom

24. LE 2-7a-2 Na  Sodium ion Cl  Chloride ion Sodium chloride (NaCl)

25. LE 2-7b Na  Cl 

31. LE 2-9 A water molecule

32. LE 2-10 Hydrogen bond

33. Figure 2.11 0

34. Figure 2.12

35. LE 2-13 Hydrogen bond Ice Hydrogen bonds are stable Liquid water Hydrogen bonds constantly break and re-form

36. LE 2-14 Ion in solution Salt crystal

39. LE 2-15 Acidic solution OH  H  H  H  H  OH  H  H  H  OH  OH  OH  OH  OH  H  H  H  H  H  H  Increasingly ACIDIC (Higher concentration of H  ) Neutral solution OH  OH  OH  OH  OH  OH  H  H  Basic solution NEUTRAL  H        pH scale Lemon juice, gastric juice Grapefruit juice, soft drink Tomato juice Human urine Pure water Human blood Seawater Milk of magnesia Household ammonia Household bleach Oven cleaner Increasingly BASIC (Lower concentration of H  )

40. Figure 2.16a 0

41. Figure 2.16b